modff.c

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MIT License
-----------
 
Copyright (c) 2002-2019 Advanced Micro Devices, Inc.
 
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#include "libm.h"
#include "libm_util.h"
 
float modff(float x, float *iptr)
{
  /* modff splits the argument x into integer and fraction parts,
     each with the same sign as x. */
 
  unsigned int ux, mask;
  int xexp;
 
  GET_BITS_SP32(x, ux);
  xexp = ((ux & (~SIGNBIT_SP32)) >> EXPSHIFTBITS_SP32) - EXPBIAS_SP32;
 
  if (xexp < 0)
    {
      /* abs(x) < 1.0. Set iptr to zero with the sign of x
         and return x. */
      PUT_BITS_SP32(ux & SIGNBIT_SP32, *iptr);
      return x;
    }
  else if (xexp < EXPSHIFTBITS_SP32)
    {
      /* x lies between 1.0 and 2**(24) */
      /* Mask out the bits of x that we don't want */
      mask = (1 << (EXPSHIFTBITS_SP32 - xexp)) - 1;
      PUT_BITS_SP32(ux & ~mask, *iptr);
      return x - *iptr;
    }
  else if ((ux & (~SIGNBIT_SP32)) > 0x7f800000)
    {
      /* x is NaN */
      *iptr = x;
      return x + x; /* Raise invalid if it is a signalling NaN */
    }
  else
    {
      /* x is infinity or large. Set iptr to x and return zero
         with the sign of x. */
      *iptr = x;
      PUT_BITS_SP32(ux & SIGNBIT_SP32, x);
      return x;
    }
}